1. Field of the Invention
The invention relates to a hydrogen combustion system which treats hydrogen by combustion with hydrogen combustion catalyst. More specifically, it relates to a hydrogen combustion system suitable for reacting excess hydrogen gases safely, including, though having no restriction as to kinds of feed hydrogen gases to be combusted, extra hydrogen gas generated during an operation of fuel cells, ambient atmosphere hydrogen gas at a film forming step in semi-conductor processes, electrolytically by-produced hydrogen gas from a water electrolysis system, by-product hydrogen gas from chemical reaction processes, to be discharged as water vapor from the processes.
2. Description of the Related Art
In general, hydrogen gases by-produced in various processes, which intrinsically involve high possibilities of explosion and leakage hazard are discharged into ambient atmosphere via exclusively provided vent pipes or via common pipes after being diluted with air by units like a blower to a point below the combustible ranges.
However, these methods require additional installation and capital investment covering hydrogen gas vent piping, equipment and machinery like a blower, and introduction of discharge systems for securing safety. For a large-scale plant, installing these equipment and systems may be inevitable, but for a small-scale process, any safe and simple treatment method of hydrogen gas has been looked for.
In order to solve these problems, various kinds of hydrogen combustion systems have been proposed. As one of these conventional equipments, for instance, such a system has been known, as shown in FIG. 7, as hydrogen gas is blown to the air supplied by a blower 10 to generate gas mixture; then the gas mixture is passed through the treatment layer 11 loaded with catalyst-supported substance in pellet, granule, honeycomb, etc., during which hydrogen gas is combusted. (JP 3-38523 A-Utility Model)
As another hydrogen combustion treatment system by a conventional method, the system has been known, as shown in FIG. 8, comprising a catalyst supported, a membrane-state element of micro porosity with nearly uniform opening 12, a hydrogen chamber 13 and a duct part 14 formed on the both sides, and a hydrogen distribution nozzle 15 in the hydrogen chamber 13, wherein the membrane element 12 has a conformation of a fine mesh (approx 10-100 μm) stainless-steel filter with catalyst of platinum, etc. on the surface. In this system, hydrogen gas is introduced to a nozzle 15; while to the duct part 14, air is forcibly flown by a fan 16. Hydrogen gas is supplied to a hydrogen chamber 13 by a nozzle 15 dispersively, diffused at micro-uniform velocity on the membrane element 12, allowed to be in contact with catalyst at passing, mixed with air flowing in a duct part 14, and thus combustively treated. (JP 2000-291917 A)
However, in the system of JP 3-38523 A-Utility Model, hydrogen gas and air are mixed first and then the mixed gas with diluted hydrogen is supplied to the treatment layer 11 at a substantially increased flow rate for hydrogen; because of this feeding mode, a large resistance occurs when the mixed gas passes through the catalyst layer. As a result, a high pressure turbo-type blower is required and the volume of catalyst must be increased, which leads to a problem of high cost from enlarged equipment.
On the other hand, the system of JP 2000-291917 A employs, as hydrogen combustion catalyst, a membrane-state catalyst, not in pellet state, but of a fine mesh (approx 10-100 μm) stainless-steel filter with platinum catalyst, etc. on the surface. This system provides insufficient air convection within the hydrogen combustion system and the temperature in the hydrogen combustion system does not rise to a level necessary for hydrogen combustion. Accordingly, in order to achieve an efficient hydrogen combustion reaction, it is necessary to feed air for hydrogen combustion forcibly using a fan 16 to a duct part 14 of the hydrogen combustion system, which requires large electric power and equipment.